1. Technical Field
The present invention relates to a media processing device having a reversing conveyance path for reversing the front and back sides of printing paper or other sheet media, and a reversing conveyance mechanism that conveys the medium through the reversing conveyance path.
2. Related Art
Examples of such media processing devices include printers with an automatic two-sided (duplex) printing capability, and scanners and fax machines with an automatic two-sided (duplex) scanning (reading) capability. In a printer with a duplex printing capability, the printing paper is first conveyed through a conveyance path past the printing position of the printhead, and the first side (front) is printed. The paper is then fed from this conveyance path into a reversing conveyance path and conveyed through the reversing conveyance path to reverse the front and back sides. The reversed paper is then returned from the reversing conveyance path to the main conveyance path and fed through the main conveyance path again to print on the back side.
JP-A-2010-280454 discloses a printer of this type. In the printer described in JP-A-2010-280454 the conveyance mechanism that conveys the printing paper through the conveyance path past the printing position, and the conveyance mechanism for reversing the paper, are driven by separate drive sources.
Synchronizing and controlling driving two conveyance mechanisms with separate drive sources so that the conveyance speeds of the conveyance mechanisms are exactly the same is difficult. As a result, when the media is passed between the two conveyance mechanisms, the media may go slack or be pulled with too tension due to the difference in the conveyance speeds, and media conveyance is therefore not stable.
Japan Patent No. 4111497 teaches technology for absorbing the difference in the conveyance speeds of the two conveyance mechanisms when the medium is passed therebetween. The technology disclosed in Japan Patent No. 4111497 provides the conveyance roller of the conveyance mechanism on the side that supplies the media with a one-way clutch that spins freely due to the difference in conveyance speed, and drives the conveyance mechanism on the media supply side at a slower conveyance speed than the conveyance speed of the conveyance mechanism on the side that receives the media. The technology disclosed in Japan Patent No. 4111497 enables absorbing the difference in conveyance speed because the paper feed roller of the conveyance mechanism on the side supplying the medium turns following the medium conveyed by the conveyance mechanism on the side that receives the medium.
The difference in the conveyance speeds of the conveyance mechanism and the reversing mechanism can be absorbed by applying the technology disclosed in Japan Patent No. 4111497 to the printer disclosed in JP-A-2010-280454. However, this increases the manufacturing cost of the device because disposing a one-way clutch to the paper feed roller of the conveyance mechanism increases the number of parts.